The first time I watched 500 Days of Summer, I misinterpreted it completely. I took what I saw at face value and missed the point. It’s an easy thing to do because the movie is heavily skewed toward the protagonist’s point of view rather than an objective look on the plot and the characters. Eventually, I got it (after rewatching the movie many times), but it was only when I talked to another student in RTA did I realize that there were one clue in particular that made the underlying message so obvious: the use of colour.
You can read more about the application of colour in 500 Days of Summer here if you want (there will be spoilers!)
There are lots of movies/TV shows that are very deliberate with their colour palette, and they stick out because of it. One of my favourite examples is the movie Her where the cinematographer, Hoyte Van Hoytema, decided to get rid of the colour blue in the film. It created a future world that was different than the normal, sci-fi, futuristic setting. It stood out.
Colour is huge. It can change the mood for any piece of art. On their own certain colours evoke feelings, but a colour palette can play a big role in a story.
On a side note: digital colourists are super cool. http://nofilmschool.com/2015/01/colorists-most-appreciated-people-post-production